Search Publications
Onset of collisionless magnetic reconnection in two-dimensional current sheets and formation of dipolarization fronts
Sitnov, M. I.; Swisdak, M.
The onset of reconnection in 2-D current sheet equilibria that include an X line separating tail-like regions with magnetized electrons is simulated with a full-particle code. The onset is driven by a finite convection electric field applied outside the current sheet. In the case of tearing stable tails with no accumulated magnetic flux, the conve…
The Supernova Impostor Impostor SN 1961V: Spitzer Shows That Zwicky Was Right (Again)
Kochanek, C. S.; Stanek, K. Z.; Szczygiel, D. M.
SN 1961V, one of Zwicky's defining Type V supernovae (SNe), was a peculiar transient in NGC 1058 that has variously been categorized as either a true core-collapse SN leaving a black hole (BH) or neutron star (NS) remnant, or an eruption of a luminous blue variable star. The former case is suggested by its possible association with a decaying non-…
The Effect of Environment on Shear in Strong Gravitational Lenses
Zabludoff, Ann I.; Keeton, Charles R.; Momcheva, Ivelina G. +2 more
Using new photometric and spectroscopic data in the fields of nine strong gravitational lenses that lie in galaxy groups, we analyze the effects of both the local group environment and line-of-sight (LOS) galaxies on the lens potential. We use Monte Carlo simulations to derive the shear directly from measurements of the complex lens environment, p…
A lepto-hadronic model for high-energy emission from FR I radiogalaxies
Romero, G. E.; Medina, M. C.; Reynoso, M. M.
Context. The well known radiogalaxy Cen A has been recently detected as a source of very high energy (VHE) γ-rays by the HESS experiment just before Fermi/LAT detected it at high energies (HE). The detection, together with that of M 87, established radiogalaxies as VHE γ-ray emitters.
Aims: The aim of this work is to present a lepto-hadronic …
Titan's cloud seasonal activity from winter to spring with Cassini/VIMS
Le Mouélic, S.; Rodriguez, S.; Sotin, C. +9 more
Since Saturn orbital insertion in July 2004, the Cassini orbiter has been observing Titan throughout most of the northern winter season (October 2002-August 2009) and the beginning of spring, allowing a detailed monitoring of Titan's cloud coverage at high spatial resolution with close flybys on a monthly basis. This study reports on the analysis …
Kinetic Structure of the Electron Diffusion Region in Antiparallel Magnetic Reconnection
Egedal, J.; Daughton, W.; Chen, L. -J. +2 more
Strong electron pressure anisotropy has been observed upstream of electron diffusion regions during reconnection in Earth’s magnetotail and kinetic simulations. For collisionless antiparallel reconnection, we find that the anisotropy drives the electron current in the electron diffusion region, and that this current is insensitive to the reconnect…
The morphology of galaxies in the Baryon Oscillation Spectroscopic Survey
Ross, Nicholas P.; Schneider, Donald P.; Weaver, Benjamin A. +17 more
We study the morphology and size of the luminous and massive galaxies at 0.3 < z < 0.7 targeted in the Baryon Oscillation Spectroscopic Survey (BOSS) using publicly available Hubble Space Telescope (HST) imaging, and catalogues, from the COSMic Origins Survey (COSMOS). Our sample (240 objects) provides a unique opportunity to check the visua…
Black hole growth in the early Universe is self-regulated and largely hidden from view
Schawinski, Kevin; Gawiser, Eric; Volonteri, Marta +2 more
The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. Although some black holes with masses more than 109 times that of the Sun have been detected in luminous quasars less than one billion years after the Big Bang, thes…
The Initial Mass Function and Disk Frequency of the ρ Ophiuchi Cloud: An Extinction-limited Sample
Meyer, Michael R.; Erickson, Kristen L.; Wilking, Bruce A. +2 more
We have completed an optical spectroscopic survey of an unbiased, extinction-limited sample of candidate young stars covering 1.3 deg2 of the ρ Ophiuchi star-forming region. While infrared, X-ray, and optical surveys of the cloud have identified many young stellar objects (YSOs), these surveys are biased toward particular stages of stel…
L1157-B1: Water and Ammonia as Diagnostics of Shock Temperature
Codella, C.; Ceccarelli, C.; Caselli, P. +5 more
We investigate the origin and nature of the profiles of water and ammonia observed toward the L1157-B1 clump as part of the HIFI CHESS survey using a new code coupling a gas-grain chemical model with a parametric shock model. First results from the unbiased survey reveal different molecular components at different excitation conditions coexisting …